OK, I'll try to help you with this ?(maybe). Scientifically speaking, a race is a subspecie of a specie; therefor Humans are a single species and "Caucasoid", "Negroid", "Mongoloid", etc. are possible subspecies, but there is still some degree of controversy about this within the Biological and Social Sciences. I would say that at present it's a convenient classification for scientific use, and I in no way agree with racism. Remember this: We are all human, and for a few very good reasons. One reason has to do with Biology: We can all interbreed. I'm afraid that my knowledge of how 'races' came about is severely limited at this time. Some biologists and anthropologists say that there is no such thing as 'race' in humans. Maybe someone else can answer about jumping higher, swimming, and the origin of 'races'. And NO, it doesn't sound stupid; your doing something all curious people do, and it's admirable: your asking ?'s.